1. Field of the Invention
The present invention relates to a method for forming a pattern using a printing method, and particularly, to a method for forming a pattern using a printing roll having convex patterns.
2. Description of the Related Art
A display device, especially a flat panel display such as a liquid crystal display (LCD) device, is driven by an active device such as a thin film transistor at each pixel. The driving method is called as an active matrix driving method. According to the active matrix driving method, the active device is arranged at each pixel in a matrix form to drive a corresponding pixel.
FIG. 1 is a view showing an active matrix type LCD device. The LCD device is a TFT LCD device in which a thin film transistor is used as an active device. As shown, at each pixel of the TFT LCD device where N×M pixels are arranged horizontally and vertically, a TFT is formed at the crossing of a gate line 4 to which a scan signal is applied from an external driving circuit and a data line 6 to which an image signal is applied. The TFT includes a gate electrode 3 connected to the gate line 4, a semiconductor layer 8 formed on the gate electrode 3 and activated as a scan signal is applied to the gate electrode 3, and a source/drain electrode 5 formed on the semiconductor layer 8. A pixel electrode 10 is formed at a display region of the pixel 1. The pixel electrode 10 is connected to the source/drain electrode 5 and operates the liquid crystal (not shown) by receiving an image signal through the source/drain electrode 5 as the semiconductor layer 8 is activated.
FIG. 2 is a view showing a structure of a TFT arranged at each pixel. As shown, the TFT includes a substrate 20 formed of a transparent insulating material such as glass, a gate electrode 3 formed on the substrate 20, a gate insulating layer 22 formed on the entire surface of the substrate 20 on which the gate electrode 3 is formed, a semiconductor layer 8 formed on the gate insulating layer 22 and activated as a signal is applied to the gate electrode 3, a source/drain electrode 5 formed on the semiconductor layer, and a passivation layer 25 formed on the source/drain electrode 5 for protecting the device.
The source/drain electrode 5 of the TFT is electrically connected to a pixel electrode formed in a pixel, and displays an image by driving the liquid crystal as a signal is applied to the pixel electrode through the source/drain electrode 5.
In the active matrix type LCD device, each pixel has a size corresponding to several tens of μm. Accordingly, the active device such as the TFT arranged in the pixel has to have a minute size corresponding to several μm. Moreover, as the consumer's demand for a display device of a high image quality such as an HDTV is increased, more pixels have to be arranged on a screen of the same area. Accordingly, an active device pattern arranged in each pixel (including a gate line pattern and a data line pattern) has to also be formed to have a minute size.
In order to fabricate an active device such as a TFT according to the related art, a pattern, a line, etc. of the active device are formed by a photolithography process by an exposing device. However, the photolithography process is composed of a series of processes such as a photoresist deposition, an alignment process, an exposure process, a develop process, a cleaning process, etc.
Also, a plurality of photolithography processes should be repetitively performed to form the pattern for the LCD device, thereby reducing productivity.